Synthesis, characterization, X-ray structure and DNA binding study of palladium(II) complex with new thioether containing ONS donor ligand

Abstract

A palladium(II) complex, [Pd(L)Cl] (1) with a new ONS donor azo–thioether ligand (L) (where L = 2,4-dihydroxy-5-((2-(methylthio)phenyl)diazenyl)(phenyl)(phenyl)methanone) is successfully synthesized. The ligand and complex are thoroughly characterized by several spectroscopic techniques. The geometry of the complex is confirmed by single-crystal X-ray analysis. Electronic structure and spectral properties are interpreted by DFT and TDDFT calculations. The interaction of the complex with CT DNA was investigated by UV-vis method and binding constant is found to be 5.42 × 104 M−1. Competitive binding titration with ethidium bromide (EB) by fluorescence titration method was carried out to understand the efficiency of the complex to displace EB from EB-DNA complex. From fluorescence titration Stern-Volmer dynamic quenching constants, Ksv was calculated and is found to be 4.15 × 104 M−1. Cyclic voltammogram of the complex exhibits significant shifting of the reduction couple to the negative potential region and decrease in current height in the presence of CT DNA. SYNOPSIS A palladium(II) complex, [Pd(L)Cl] (1) with a new ONS donor azo–thioether ligand (L) (where L = 2,4-dihydroxy-5-((2-(methylthio)phenyl)diazenyl)(phenyl)(phenyl)methanone) is successfully synthesized and characterized. The geometry of the complex is confirmed by single-crystal X-ray analysis. Electronic structure and spectral properties are interpreted by DFT and TDDFT calculations. The interaction of the complex with CT DNA is investigated by UV-vis, fluorescence and cyclic voltammetric method.